The present invention relates to a method for the hydroformylation of olefins by reaction with carbon monoxide and hydrogen in the presence of soluble cobalt compounds at an elevated temperature under increased pressure, producing the corresponding alcohols which contain one more carbon atom.
The state of the prior art of the oxo process and of cobalt catalysts used therein may be ascertained by reference to the Kirk-Othmer "Encyclopedia of Chemical Technology", Vol. 14 (1967) under the section "Oxo Process", on pages 373-390, particularly pages 375-376, which disclose the cobalt catalysts, and pages 383-384, which disclose the catalyst removal and recovery, and U.S. Pat. Nos. 2,767,048, 2,816,933 and 2,841,617 of Joseph K. Mertzweiller, which issued Oct. 16, 1956, Dec. 17, 1957 and July 1, 1958, respectively.
In the hydroformylation of olefins with carbon monoxide and hydrogen according to the oxo process, high conversion rates are desirable, because unreacted olefins are converted into less valuable paraffins during the hydrogenation necessary during the course of the usual working-up procedure.
Although high conversion rates can be forcibly obtained even in case of sluggishly reacting olefins by means of high catalyst concentrations, these favor, on the other hand, the formation of undesirable higher boiling by-products and thereby impair the alcohol yield. An increase in the temperature and an extension of the residence time have a similarly adverse effect on the yield. The latter furthermore reduces the space time yield and thus is a burden on the economy of the process.
Propene can be reacted, due to its high reaction velocity, with CO and H.sub.2 with satisfactory space time yields at a residence time of 1-2 hours (J. Falbe, Ullmanns Encylkopaedie der technischen Chemie (Ullmann's Encyclopedia of Technical Chemistry) 3rd Ed., 1970, Supplemental Volume, p. 90). The reaction velocity of the olefins decreases with an increasing chain length and with an increasing degree of branching (J. Falbe, "Synthesen mit Kohlenmonoxid" (Synthesis with Carbon Monoxide), Springer publishers, 1967, p. 29). Although it is still economical to subject higher .alpha.-olefins to hydroformylation by means of the heretofore known reaction conditions and reactors, this becomes impossible for higher olefins having an internally positioned double bond and for olefins having branched carbon chains wherein the reaction velocity is only 1/3 of the reaction speed of .alpha.-olefins having the same chain length (J. Falbe, loc. cit.).